Some jurisdictions do put a limit on how they define next of kin (please see the legal treatise Unnatural Death , supra , for guidance on English law), and other jurisdictions don’t put a limit.
Here’s the guidebook put out by the Ontario Public Guardian and Trustee:
And here’s the relevant part:
15. Who is entitled to the money from estates administered by the OPGT?
The Succession Law Reform Act sets out, in order of priority, which next of-kin are entitled to inherit if a deceased person did not make a Will (this is called “intestate”). Even very distant relatives may be entitled to inherit if there are no next-of-kin closer in relationship.
If the deceased did make a Will, the persons named as beneficiaries in the Will are entitled to the money in accordance with the deceased’s instructions.
The OPGT conducts a careful and thorough search for heirs. If none can be found within 10 years, the money is transferred from the OPGT to the provincial government’s general account. However, it can still be claimed by heirs who come forward after that. Entitlement to the money that is transferred is never lost.
16. How does the OPGT find the heirs?
Sometimes the next-of-kin can be identified by reviewing the deceased’s personal papers. Sometimes they are identified by others, such as the deceased’s caregivers, lawyer or friends. In these cases, it is usually a fairly simple matter of determining which of the next-of-kin are entitled by law to inherit, and then making contact and receiving proof of their identity and their relationship to the deceased.
In many cases, however, it is very hard to identify and locate next-of-kin. The OPGT often retains professional genealogists to trace the deceased’s family tree. These experts use a variety of techniques including searching birth, marriage, death notices and records in Canada and abroad.
So, sounds pretty thorough, in Ontario at least. (I’ve put bolding on a couple of points in the two paragraphs.)